Leopards and lions have been known to mix it up over meals on occasion.
Lions are much bigger than leopards, so when conflicts do arise the spotted cats typically go with the flight option instead of the fight option.
But when your backs against a wall and flight isn’t an option, then ya gotta fight. This particular leopard was presumably relaxing in the tree tops and consuming whatever it had recently hunted.
A lioness must have smelled what the other cat was cooking, as the footage picks up with the hungry feline already going up the tree. The two heavy weight fighters were more than the tree branches could handle though, as both cats, and half the tree, eventually come crashing to the ground.
At that point the leopard gets the hell up out of there before the lion causes any more damage.